Image projection system

• US 6,375,327 B2
• Filed: 04/10/2001
• Issued: 04/23/2002
• Est. Priority Date: 09/30/1996
• Status: Expired due to Term

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: DOIC, Inc.
• Inventors: Holman, Robert L., Cox, Arthur
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US09/829,687
• Time in Patent Office: 378 Days
• Field of Search: 353/20, 353/8, 353/31, 353/33, 353/34.37, 353/94, 353/98.99, 349/5, 349/8, 349/9, 359/464, 359/465, 359/472, 359/497, 359/501, 359/494, 359/495
• US Class Current: 353/20
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G03B 21/62 Translucent screens

Abstract

An image projection device having a spatial light modulator and a polarized source system for illuminating the spatial light modulator such that light of a first polarization state illuminates one region of the spatial light modulator and light of a second polarization state illuminates another region of the spatial light modulator. Preferably, the image projection device includes a first set of polarization selective light processing elements, including a first conicoid element which passes light of the first polarization state and reflects light of the second polarization state and a second set of polarization selective light processing elements including a second conicoid element which passes light of the second polarization state and reflects light of the first polarization state.

Claims

1. An illuminating system, comprising:

an output screen including a liquid crystal display (LCD),

means for generating white light;

a light source system for illuminating said output screen with polarized light such that a first portion of light of a first polarization state from the means for generating light is output for imaging without change of polarization state and a second portion of light of a second polarization state is converted to polarized light of the first polarization state for display on said screen, said light source system including;

(a) a first polarization selective light processing element including a conicoidal light processing element whose vertex contains a small inlet that receives light from the means for generating white light and the small inlet passes a focused high numerical aperture white light of mixed polarization state and the conicoidal light processing element converts the white light incident on a surface of the conicoidal light processing element from a first circular polarization state into reflected light of a second circular polarization state, the second circular polarization state being orthogonal to that of said first circular polarization state;

(b) a second polarization selective light processing element including a first element which reflects light of a second linear polarization state and also transmits light of a first linear polarization state and further including a second optical element for converting light of the second linear polarization state into light of second circular polarization state and upon reflecting from said conicoidal light processing element becomes light of said first linear polarization state, thereby enabling output through the first light processing element of light of the first linear polarization state onto the output screen; and

said output screen including at least one of a Fresnel lens and a diffuser for converting the light of the first linear polarization state passed through said Fresnel lens into output beams of specific angular extent to the LCD display which receives output light.

2. An illuminating system, comprising:

an output screen including a liquid crystal display (LCD),

means for generating white light;

a light source system for illuminating said output screen with polarized light such that a first portion of light of a first polarization state from the means for generating light is output for imaging without change of polarization state and light of a second polarization state is converted to polarized light of the first polarization state for display on said screen, said light source system including;

(a) a first polarization selective light processing element including a conicoidal light processing element whose vertex contains a small inlet that receives light from the means for generating white light and the small inlet passes a focused high numerical aperture white light of mixed polarization state and the conicoidal light processing element converting the white light incident on a surface of the conicoidal light processing element from a first circular polarization state into reflected light of a second circular polarization state, the second circular polarization state being orthogonal to that of said first circular polarization state;

(b) a second polarization selective light processing element including a first element which reflects light of a first linear polarization state and also transmits light of a second linear polarization state and further including a second optical element for converting light of the first linear polarization state into light of the first circular polarization state and upon reflecting from said conicoidal light processing element becomes light of said second linear polarization state, thereby enabling output through the first light processing element of light of the second linear polarization state onto the output screen; and

said output screen including at least one of a Fresnel lens and a diffuser for converting the light of the second linear polarization state passed through said Fresnel lens into output beams of specific angular extent, a polarizer for at least one of absorbing and reflecting the light of said first linear polarization state and transmitting the light of said second linear polarization state to said LCD screen which receives output light.